Immigrants perish in the desert year after year in attempts to cross the U.S.-Mexico border. Many of these deaths, especially in the summer, are linked directly to heat stroke.

Sam Keim is an associate professor and vice head and residency director of the Department of Emergency Medicine at the University of Arizona and has recognized heat stroke deaths among immigrants as a pending problem. In an effort to better understand this issue, Keim has created a model that predicts the amount of border-related deaths based on the weather.

In 1999, a student-doctor commented to Keim about how the emergency department was starting to see a larger influx of immigrants with heat stroke cases than usual. Keim was intrigued by this issue and decided to start a research program designed to measure the amount of heat stroke-related deaths among those crossing the border.

Recently, Keim has developed a model that links the dates of deaths of immigrants who died of heat stroke to the high temperatures that occurred on that same exact date.

“The model presents the probability that one or more individuals will die of heat stroke within Pima County that day,” Keim said.

Keim says the model, included on a Web site he created, continuously displays the probability of heat-related deaths year round by using the National Weather Service's 5-day forecast to create a Pima County five-day forecast.

Many immigrants have continued to cross the border despite the heat and widespread notices on both the U.S. and Mexico side of the border, according to Keim.

Keim and his research team are currently in the process of conducting interviews in Mexico with immigrants who have been deported. Keim says many of the people who have been interviewed either did not realize the severity of the trek across the border, or simply thought they would be one of the lucky ones.

“It seems that many of them were unclear about the dangers,” Keim said.

And many of those dangers worsen with the brutal summer heat.

Keim said that essentially all of the heat stroke-related deaths occur in the summer.

“The probability that a day will have one or more deaths begins to increase when the temperatures are even in the 90s, but it really takes off in the early 100s.”

When the temperature has reached 105 degrees, the probability that there will be one or more deaths that day approaches 50-percent.

“That's really significant,” Keim said. “If we could say that the risk of death from other diseases on a given day in Pima County was 50 percent, people would really take notice.”

Though the temperatures are cooling down and Fall is nearly in full swing, a probability of border-related deaths due to heat still occurs almost daily. Keim’s Web site, crossingRisk, showed a six percent probability of heat-related death with a high of 86 degrees on Monday, Nov. 19.

To observe the probability of border-related deaths, visit Sam Keim's Web site.


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"Peligro En El Desierto" (English)

"Peligro En El Desierto" (Spanish)